Organ transplantation has been successfully used to replace or repair damaged tissues. However, transplantation is limited by the availability of donors, and the high costs and radical nature of the surgery. It is evident that alternative procedures to transplantation are desirable.
The grafting of healthy cells into diseased tissue has been proposed as an alternative to organ transplantation. However, the success of such grafts is dependent upon the developmental stage of the injected cells. Adult cells generally do not incorporate into tissue but early stage embryonic cells stably integrate. Embryonic cell grafts are not preferred due to the ethical issues involved, and technical and availability limitations. Thus, there is a need for alternative sources of cells capable of integration into tissues. In particular, a need exists for cell preparations containing cells of various tissues for transplantation in which (1) the preparation is accepted by the patient, thus avoiding the difficulties associated with immunosuppression, (2) the preparation is safe and effective, thus justifying the cost and effort associated with treatment, and (3) the preparation is efficacious during and after transplantation.
Bone marrow transplantation is a common form of therapy for a number of diseases involving dysfunction of hematopoietic cells, or which involve treatments which irreversibly damage hematopoietic cells (e.g. chemotherapy and radiotherapy for cancer). The use of bone marrow transplantation has allowed more intensive and effective chemotherapy and radiotherapy for cancer. However, the approach requires an adequate number of stern cells to ensure success. Thus, there is a need for sources of hematopoietic stem cells that will reduce the risk of graft versus host rejection and provide an adequate number of stem cells for transplantation.
The citation of any reference herein is not an admission that such reference is available as prior art to the instant invention.